1. Field of the Invention
The invention relates to a tipping conveyor element for a package conveyor, in practice also indentified in brief as a sorter.
2. Discussion of the Background
A driven conveyor line of the above-noted type comprises a plurality of conveyor elements flexibly connected to one another. At least one package is placed on an essentially horizontal carrying surface while a tippable element is in a conveying condition. By tipping of the carrying surface, producing a tilt, the package is delivered, as desired, to one of several delivery stations provided laterally to the conveyor direction along the conveyor track. A carrying element contains the carrying surface. The carrying element is supported by a support device mounted on a support part movable along a guide. The carrying element is mounted to be rotatable around a swivel axis by means of a shaft extending obliquely downward from its underside relative to the support part. The swivel axis lies in a common vertical plane (also identified below as the "initial plane") with a plane of symmetry of the carrying element or its carrying surface when the carrying element is in the conveying condition. It is angled in the conveyor direction and forms an acute angle with the carrying surface.
The packages are so fed to a sorter at one feed point at least (but often also at several feed points) that in each case they are placed, when the conveyor element is in the conveying condition, on the essentially horizontal carrying surface of a conveyor element. When above or hereafter it is said that the carrying surface of the conveyor element in the conveying condition is "essentially" horizontal, this is to include the following variations. The carrying surface optionally can also be curved or bent in the shape of a dish. The conveyor line can run in a horizontal plane, but also obliquely to the horizontal or in other directions, in which case care is to be taken that the packages do not involuntarily slide down from the carrying surfaces.
The essential object of a sorter consists in delivering in each case the packages to one of the several delivery stations placed laterally to the conveyor track to sort them according to specific criteria. In the case of mail parcels this can be, for example, a sorting according to zip codes or in the case of a sorter used at an airport, a sorting of checked in pieces of luggage according to flight destination or the like. In this connection, the packages are generally provided with a code before their delivery to the sorter or they exhibit a marking from the beginning, which is readable by a reading device after their check-in, whereby the code or marking is assigned to a specific delivery station, and by certain devices care is taken that a package assigned to a specific delivery station is delivered to it laterally from the sorter. At the respective delivery point the package is sent, generally by a chute, to a conveyor having a conveyor direction running crosswise to the sorter, from which it is reconveyed for further processing.
To accomplish the desired delivery of a package to a specific delivery station, obviously it would be basically possible to shove the package laterally from the carrying surface (in this case, the carrying surface remaining essentially horizontal) of the respective conveyor element, using in each case a stamp or the like running essentially crosswise to the conveyor direction of the sorter. However, such a mode of operation is unsatisfactory, especially in the case of the high conveyor speeds of sorters achieved today, which are up to 2 m/sec and more, if only because the package, with such a delivery, is placed under exceptionally heavy stress. However, as gentle as possible handling of the package in practice is highly desired for all cases of using sorters.
Therefore, conveyor elements have been developed for such package conveyors, in which the carrying surface, at a delivery station, is rotated around a swivel axis placed centrally of the carrying surface and running in the conveyor direction. The central arrangement of the swivel axis to the carrying surface was therefore especially chosen to accommodate, for example, the case of such a sorter in which the delivery points are placed on the left and right of the conveyor track, so that consequently the package must also optionally be delivered either to the left or right. However, this previously known design of a conveyor element for a sorter or the like has proved disadvantageous, because a package located centrally on the carrying surface of the conveyor element is lifted during lateral tipping to the other side of the carrying surface, so that during delivery of the package a tumbling of the package occurs. Here, too, a hardly gentle handling occurs. This is particularly also the case if a package is laterally offset on the carrying surface toward a side thereof that is opposite to the delivery side, in other words, essentially toward that side of the carrying surface which is lifted during tipping. In addition, in the case of a lateral tipping of the carrying surface in a way described above, an oblong package which, i.a., is laid on a conveyor element in its longitudinal direction is so delivered from the sorter that its long side is forward, so that the receiving or transfer devices must be designed correspondingly wide or be provided with corresponding deflection devices, which again does not result in gentle package handling and moreover results in a correspondingly greater expense.
At least to reduce the danger of a tumbling or spinning of a delivered package, conveyor elements have already become known, in which the swivel axis running in the conveyor direction for tipping of the carrying surface is laterally offset with respect to the longitudinal axis of symmetry of the carrying surface. However, such an offset, i.a.--especially with comparitively large carrying surfaces--is not to be achieved in such a way that the swivel axis essentially is disposed in the area of a lateral longitudinal edge of the carrying element. In such a case, the carrying surface, horizontal in the conveying condition, in the case of a lateral tipping is essentially dropped only downward. Therefore, only a relatively small offset of the swivel axis with respect to the longitudinal axis of symmetry is feasible, as a result of which the danger of a tumbling (spin) of the respective package cannot be sufficiently reduced. But since the carrying surface of a conveyor element under discussion here, generally because of the reasons already mentioned above, must be able to be tipped optionally to the left or right, such a configuration for changing over from one swivel axis to the other swivel axis in addition requires a considerable expenditure, which is not only linked to the corresponding costs but also is correspondingly prone to breakdown because of the relatively complicated mechanism. Moreover, with this previously known conveyor element, oblong packages are so delivered by the sorter that their long side is in front, so that, by and large, the disadvantages already mentioned above are present and, moreover, no gently package handling is attained.
For more suitable delivery from the carrying surface of the respective conveyor element of an oblong package placed on a conveyor element, and at the same time for more gentle handling of the package, it would obviously be more suitable during the delivery to impart to the package a turning movement in addition to the tipping movement. However, it is to be kept in mind that the delivery must take place to the smallest space and, in view of the high conveyor speeds of such sorters, in the shortest time, so that, for example, there would occur a first resulting rotation of the carrying element exhibiting the carrying surface around a vertical axis, and only then would begin the tipping of the carrying surface. Such cannot be achieved under pracitcal conditions.
However, an overlapping of a lateral tipping movement with a rotation movement of the carrying surface is possible if the carrying element, during delivery of a package, is rotated not around a vertical swivel axis but around a swivel axis set at an angle to the vertical, whereby the carrying element is mounted to be rotatable around a swivel axis by means of a shaft extending obliquely downward from the underside of the carrying element and relative to a support part carried by the conveyor guide and prevented from rotation by the guide. The swivel axis lies in a common vertical plane with the axis of symmetry of the carrying element or its carrying surface when the carrying element is in the conveying condition. It slopes in the conveyor direction and forms an acute angle with the carrying surface. With such a design of a conveyor element, if the shaft, solidly connected to the carrying element, is rotated around a swivel axis at a delivery point, this obviously results in a rotation of the carrying surface, horizontal in the conveying condition, around the swivel axis and thus at the same time results in a tilt of the carrying surface, so that the package supported by the carrying surface can slide off of it if a sufficient tilt of the carrying surface is achieved so that the static friction between the package and the carrying surface is overcome by gravity.
However, it has been shown that with such a conveyor element no optimal delivery of the package with a view to a gentle handling of the package can be attained. Moreover, the rotation around the swivel axis to be imparted to the axis of rotation at a delivery station so far has not been solved either in regard to cost or to proneness to breakdown.